The present invention relates to a seal for a sensor element having a ceramic element in the form of a solid electrolyte element embodied as a closed tube and fastened in a sealable manner to a metallic housing. The seal of the present invention is implemented between the solid electrolyte element and the housing.
German Published Patent Application No. 43 42 731 describes sensors based on solid electrolytes in which electrically conductive metal or graphite sealing rings are used for sealed immobilization of the solid electrolyte element in the housing. The metal sealing rings are moreover often covered with a galvanically deposited copper layer. At elevated temperatures, this leads to oxidation and corrosion of the metal or graphite surface. It can moreover cause the metal ions which are thereby created to diffuse into the solid electrolyte or into layers which are arranged on the surface of the solid electrolyte, such as conductive paths, cover layers, and insulation layers. This modifies and impairs their properties in terms of proper function.